Python实现的一个简单的状态框架，python实现框架,from time im

Python实现的一个简单的状态框架，python实现框架,from time im

from time import sleepfrom random import randint, shuffleclass StateMachine(object):    ''' Usage:  Create an instance of StateMachine, use set_starting_state(state) to give it an        initial state to work with, then call tick() on each second (or whatever your desired        time interval might be. '''    def set_starting_state(self, state):        ''' The entry state for the state machine. '''        state.enter()        self.state = state    def tick(self):        ''' Calls the current state's do_work() and checks for a transition '''        next_state = self.state.check_transitions()        if next_state is None:            # Stick with this state            self.state.do_work()        else:            # Next state found, transition to it            self.state.exit()            next_state.enter()            self.state = next_stateclass BaseState(object):    ''' Usage: Subclass BaseState and override the enter(), do_work(), and exit() methods.             enter()    -- Setup for your state should occur here.  This likely includes adding                           transitions or initializing member variables.            do_work()  -- Meat and potatoes of your state.  There may be some logic here that will                          cause a transition to trigger.            exit()     -- Any cleanup or final actions should occur here.  This is called just                          before transition to the next state.    '''    def add_transition(self, condition, next_state):        ''' Adds a new transition to the state.  The "condition" param must contain a callable            object.  When the "condition" evaluates to True, the "next_state" param is set as            the active state. '''        # Enforce transition validity        assert(callable(condition))        assert(hasattr(next_state, "enter"))        assert(callable(next_state.enter))        assert(hasattr(next_state, "do_work"))        assert(callable(next_state.do_work))        assert(hasattr(next_state, "exit"))        assert(callable(next_state.exit))        # Add transition        if not hasattr(self, "transitions"):            self.transitions = []        self.transitions.append((condition, next_state))    def check_transitions(self):        ''' Returns the first State thats condition evaluates true (condition order is randomized) '''        if hasattr(self, "transitions"):            shuffle(self.transitions)            for transition in self.transitions:                condition, state = transition                if condition():                    return state    def enter(self):        pass    def do_work(self):        pass    def exit(self):        pass################################################################################################################################# EXAMPLE USAGE OF STATE MACHINE #####################################################################################################################################class WalkingState(BaseState):    def enter(self):        print("WalkingState: enter()")        def condition(): return randint(1, 5) == 5        self.add_transition(condition, JoggingState())        self.add_transition(condition, RunningState())    def do_work(self):        print("Walking...")    def exit(self):        print("WalkingState: exit()")class JoggingState(BaseState):    def enter(self):        print("JoggingState: enter()")        self.stamina = randint(5, 15)        def condition(): return self.stamina <= 0        self.add_transition(condition, WalkingState())    def do_work(self):        self.stamina -= 1        print("Jogging ({0})...".format(self.stamina))    def exit(self):        print("JoggingState: exit()")class RunningState(BaseState):    def enter(self):        print("RunningState: enter()")        self.stamina = randint(5, 15)        def walk_condition(): return self.stamina <= 0        self.add_transition(walk_condition, WalkingState())        def trip_condition(): return randint(1, 10) == 10        self.add_transition(trip_condition, TrippingState())    def do_work(self):        self.stamina -= 2        print("Running ({0})...".format(self.stamina))    def exit(self):        print("RunningState: exit()")class TrippingState(BaseState):    def enter(self):        print("TrippingState: enter()")        self.tripped = False        def condition(): return self.tripped        self.add_transition(condition, WalkingState())    def do_work(self):        print("Tripped!")        self.tripped = True    def exit(self):        print("TrippingState: exit()")if __name__ == "__main__":    state = WalkingState()    state_machine = StateMachine()    state_machine.set_starting_state(state)    while True:        state_machine.tick()        sleep(1)